It's something that they say a lot in publishing, apparently, that once you turn 40, you start reading biographies. I do remember in my 20s, someone nearing 40 saying, "When a novel says, 'So-and-so walked into the room,' I have this voice in my head shouting 'So? They're not real! The room isn't real!'" I thought, what an incredibly weird, sad, unexpected, unattractive side of ageing, like getting cellulite on your nose. Sure enough, though, I've found my appetite for fiction has fallen off a cliff. It's possible that this is just part of my inexorable crawl toward death. But there's a topnote of guilt, which reminds me of that wartime poster: "To dress extravagantly in wartime is worse than bad form. It is unpatriotic." When the news is so apocalyptic, and there is so much to understand, and a lot of it is quite basic (what's the point of low interest rates again? How do you devalue a currency? Why are there so many earthquakes? Tell me one more time about tectonic plates; I promise this time I'll listen … ), it feels more than frivolous to read about made-up people. It feels unpatriotic. Or, to put it another way, it is like watching the telly when you have homework.

There is a surge in popular economics books – if you look at the Penguin catalogue for next year, every second one is about money, how it works, how it doesn't work and how soon it will end.

There is a surge of books about the changing world order: India Rising, from Faber, as of course it is, but also Keeping Up With the Germans. Its author, Philip Oltermann, finished it before the crisis, and before Angela Merkel fetched up at the centre of the eurozone pantomime. He describes the eerie experience of hearing economic commentators pose exactly his question, as a matter of urgency: how on earth can everybody keep up with the Germans? The book is not straightforward economics. "It's a book about why English and German people sometimes get on and sometimes don't. It's a book that argues that, in order to understand the phenomenal success of the German economy over the past 50 years, we need to look beyond the cliche of robotic, machine-like 'efficiency' and understand why Germans are ultimately sentimental romantics, even when it comes to cars."

And that, in a way, is why I feel as if I should be reading it. It's reasonable, as an adult, to decide you don't want to read a book about the German economy, because you probably wouldn't understand it, whereas it seems unreasonable to watch a crisis unfold before your eyes, and know so little about it.

There are two questions looming over every conversation – how did we get into this mess? And who, in 10 or 20 or 30 years' time, will have come out of it? I had a sudden snap of realisation about how prevalent those questions had become when I was flicking through a book called Running With the Kenyans; I misread it as "Running With the Keynsians"; my friend misread it as "Running with the Koreans".

The key text for popular economics is John Lanchester's Whoops! Why Everyone Owes Everyone and No One Can Pay. It's sold 30,000 copies since it was published last year. (For comparison, Nobel Prize winner Paul Krugman wrote an incredibly slim, readable volume called The Return of Depression Economics, and that's sold 19,000 in three years – these are UK figures, by the way.) Lanchester wrote the book because he was researching the financial industry for a novel, Capital, which is out next year; and the intricacies of the way finance worked seemed a) so interesting and complex that they were effectively a character in their own right, and b) vitally, this was stuff nobody understood. "I felt, and still feel, that the gap between people who speak money and people who don't is actually a democratic deficit. This is the only time I've ever felt that I have a citizenly duty to keep it up. I mean, only reactively, when I'm asked." I personally am of the view that he should do a Whoops Roadshow, but that is between him and his citizenly duty – at some point you do start thinking, I should have understood this before circumstances made it alarming not to understand it.

Much of the territory of Whoops relates to financial instruments, CDOs and other toxic debt bundles. "Some of the people who didn't understand them were the directors of major banks. That should be a joke, but isn't." That counts as a mitigating factor, for the layman – but the storm we're living through now makes me realise how little I understood of any of the past 20 years, in terms of the economic foundation stones they were laying down. So to take, at random, the eurozone again: there were people objecting who weren't just dyspeptic Tories. There were also leftwing Eurosceptics, Jack Straw, the late Peter Shore, predicting exactly, to the letter, what would happen to a single currency – that the interest rates would be determined by the strongest economies, but wouldn't suit the weaker ones, which then wouldn't be able to devalue and wouldn't be able to leave. I didn't really know why a low interest rate would suit a strong economy, and I didn't understand the point of devaluation. I was too busy reading Martin bloody Amis. As if that's going to help. Lanchester says, possibly by way of reassurance, "We'd all rather be in the back seat of the car, with our parents in the front, driving. But now we've woken up doing 90." The problem with ignorance is twofold: you feel alienated and disempowered, and that's quite anxious-making, but you also feel embarrassed by the limits of your understanding, so you back out of the conversation.

When you back out of a conversation at a macro-level, that's how you wake up doing 90, with a government full of bankers and technocrats. I'm emphatically not saying, "We're all going to be Italy in a minute," because that's the kind of scaremongering nonsense that you'd only start if you hadn't just read (26 pages of) Akerlof and Shiller's Animal Spirits. The alienation effect makes it necessary, much as it pains me to say it, to understand what the parents who were driving were actually thinking: so not only do we have a citizenly duty to understand Germany, economics, the new world order, science and climate, but we probably also have to read, if not Tony Blair's autobiography, at least Gordon Brown's and/or Alistair Darling's.

But this isn't just semi-sincere self-flagellation; there is also a problem with the modern novel and its continuing fear of saying anything useful, for fear of not sounding literary enough. Everyone expected Alan Hollinghurst to write the definitive book of our recent past, since that's what he did for the 1980s, in The Line of Beauty. Instead, to use a technical publisher's term, he "did an Atonement" – this is where you re-site your large themes in the past, where they are more attractive and less political. Hannah Griffiths, editorial director at Faber and Faber, explains that this is partly a pragmatic consideration: "You'd have to write a very ambitious contemporary novel, because they take so long to come out."

Damian Barr is a writer and playwright who also runs literary salons in Shoreditch House, as a result of which he has read almost everything: "There is this false idea that fiction has no particular stance because it is made up, as a result of which it doesn't have to be informed, and it doesn't have to inform. I think we desperately need to be informed about our times, and our history, and our human condition, and at the moment, the novel is really only good for the latter. Of course, I only mean the ones worth reading." Lanchester notes: "In general, the literary novel has turned slightly too far away from the things that press on people. It is an utterly bizarre place to have ended up, but if the subject of a novel is too interesting, that's not literary enough." I can remember the beginning of falling out of love with fiction, when it began to annoy me if the main character didn't have a job or any visible means of support. Once that annoys you, you get annoyed by almost everything.

And if fiction is permeated by considerations – some practical, some literary, some pretentious, some reasonable, because long explanations of things are boring – that make it fight shy of big questions; even non-fiction shares some of this coyness. The Costa shortlist came out this week, and in the biography section, one (broadly) about the first world war, one (broadly) about the second, one biography of Charles Dickens and Patrick and Henry Cockburn's Henry's Demons: Living with Schizophrenia, a Father and Son's Story. And that last is a fine book, but Cockburn's area of expertise, won over a lifetime, is as a foreign correspondent. Yet when he writes a book about Iraq (Muqtada al-Sadr and the Fall of Iraq), about things that would be quite useful to know, especially if we're going to start attacking Iran, the mainstream acts as if it had never happened.

Of course, there's a caveat, isn't there? A novel that does take on big contemporary questions, even if it then hinges on an understanding of complex warfare, or politics, or industry, or finance, if it can do that and not be boring, not be full of what science fiction calls the "tell me, Professor" moments, that will be more use to you, probably, than any amount of explication delivered in factual, readable, lay terms. "If I've learnt anything real," Griffiths concludes, "I've learnt it through fiction."

And this point is made flesh, really, by John Lanchester, who illuminated all this nefarious financial jiggery-pokery – but Whoops was a side-dish or an amuse-bouche to the main project, Capital, a great monster of a novel, which does more than illuminate finance: it animates it; and that's when you fully comprehend something, when you can see its face.